488 CONSIDERATION OF CARBON COMPOUNDS. 



resulting in the formation of glyceryl mono-nitrate, or tri-nitrate, 

 substances belonging to the group of compound ethers, the constitu- 

 tion of which will be explained later. 



C 3 H 5 (OH) 3 + 3HN0 3 = C 3 H 5 (N0 3 ) 3 + 3H 2 O. 



The tri-nitro-glycerin is the common nitro-glyceriu, a pale-yellow 

 oily liquid, which is nearly insoluble in water, soluble in alcohol, 

 crystallizes at 20 C. ( 4 F.) in long needles, and explodes very 

 violently by concussion ; it may be burned in an open vessel, but 

 explodes when heated over 250 C. (482 F.). 



Spirit of g-lyceryl trinitrate, Spiritus g-lycerylis nitratis (Spirit 

 of glonoiri) is an alcoholic solution of nitro-glycerin, containing of this 

 substance 1 per cent. 



Dynamite. One kilogram of nitro-glycerin yields after explosion 713 liters 

 of gas, measured at normal temperature and pressure. As the gas temperature 

 is raised by explosion to about 7000 C. (13,000 F.), the volume is comparatively 

 larger, and the explosive power of nitro-glycerin compared with that of gun- 

 powder is about 13 to 1. Indeed, the explosions of pure nitro-glycerin are so 

 violent that it is generally mixed with inert substances, such as clay, sawdust, 

 infusorial (diatomaceous) earth, etc. When mixed with the latter it forms the 

 extensively used dynamite, which is more useful and less dangerous to handle 

 than pure nitro-glycerin. While it is not readily exploded by pressure or jar, 

 it is by percussion ; for instance,, by fulminating mercury explosion. 



Mixtures of nitro-glycerin and gun-cotton form explosive gelatine, or gelatine- 

 dynamite. 



Glycerin-phosphoric acid, C 3 H 5 (OH) 2 O.PO(OH) 2 . Compounds 

 of this acid are met with in blood, flesh, the brain, and the nerves. 

 It also occurs together with cholin, as a result of the splitting up of 

 lecithin (see Index). 



The absolute acid is very unstable, decomposing easily into glycerin 

 and phosphoric acid. The commercial article is a 20 per cent, aqueous 

 solution. It is obtained by dissolving gradually glacial phosphoric 

 acid in an equal weight of 95 per cent, glycerin with moderate heat, and 

 subsequently heating the mixture for several hours at 110 C. Union 

 takes place thus : 



C 3 H 5 (OH) 3 -f HPO 3 = C 3 H 5 (OH) 2 O.PO(OH) 2 . 



The tenacious mass is dissolved in water, neutralized with milk of 

 lime, and filtered. The excess of lime is precipitated by a current 

 of carbon dioxide and filtered off. The filtrate is concentrated in a 

 vacuum and precipitated with alcohol or evaporated to dryness. The 

 calcium salt is washed with alcohol to remove glycerin, dissolved in 

 water, and decomposed with a calculated amount of diluted sulphuric 

 acid. (The filtrate is evaporated to the proper concentration.) 



